064 stihl cylinder fixable?

[421SD]

I need some advice on my 064. Back story short was friends saw blew up the clutch, which took out oil pump etc. He gave it to me, fixed the damage ran good. Has 150 + comp. Took the muffler off and saw some scratches, pulled cylinder and found this. Can it be saved ? Or do I need a new cylinder and piston? Thanks for the help!

 

[JonCraig]

I'm no expert, but that wouldn't be bad enough for me to replace. I bet it'll run great. Unless there's transfer. Does a fingernail grab it?

 

[421SD]

It feels like a scratch not transfer. But it had 150lb. compression Just befor I tore it down. The rings have a lot of gap surprisingly given the good compression. I have a new set of rings for it. Thinking about throwing them in. I'm new to saws that's why I was looking for some other opinions on the damage. I rebuild automatic transmissions for a living saws are a new hobby.

 

[JonCraig]

I'd say if you can rebuild an auto trans, saws are a walk in the park.

I'd replace the rings & run it myself.

 

[421SD]

I like them because they are way less complicated. Something different than cars & trucks. I was thinking that if the worst that happens is it eats a set of ring no big deal I'll look for a piston and cylinder then. Just get some use out of it in the time being. Had a hard time finding a oil pump for it so I modded a 066 pump. It works great.

 

[BuckthornBonnie]

That cylinder will clean up. A light sand and scothbrite, then clean thoroughly.

The piston--- some would run that without hesitation and probably be fine. Maybe lightly sand it, even. New oem or caber rings would help. Personally I'd put a new Meteor or OEM piston in it. Any wear on the skirts?

Also--- how'd you mod that pump?

 

[421SD]

It's a 066 pump made into a 064 pump with the oil hose. Drill press, hacksaw, file and some spare time! After I made it I found a good used one of course. But it can be done if you can't find a 064 pump. There isn't any wear just the scratches. Looks like it got run without a air filter maybe?

 

[BuckthornBonnie]

It's a 066 pump made into a 064 pump with the oil hose. Drill press, hacksaw, file and some spare time! After I made it I found a good used one of course. But it can be done if you can't find a 064 pump. There isn't any wear just the scratches. Looks like it got run without a air filter maybe?View attachment 591350

Yep. Just wondering how ya did it. Cool stuff. 064 pumps are getting a bit rare but 660s are all over. I honestly never thought of modding one to fit an 064 case.

The wear would best be seen looking down at the skirts. Any machine marks left?

 

[421SD]

Here are a few more pics. It's the scratches that got me thinking about using it or not. The intake side of the piston looks good.

 

[BuckthornBonnie]

Nice pics.

 

[alexcagle]

I'd replace the piston.
Was it fogging out of the carb any, with the air filter off,at operating temp, while accellerating?
If so, that would indicate primary compression loss from wear at the intake skirt.

 

[alexcagle]

Nice pics.

*
Yep.
Most of us guys like a close up skirt pic. lol
(as long as the skirt doesn't care)

 

[drf255]

The damage to that cylinder doesn't look to have been caused by that piston, at least to me.

I'd replace it. Those look like deep scratches, not just transfer. They don't line up with the piston damage. Looks like it was reconditioned before it hit your buddy's saw.

064 cylinders aren't all that hard to come by. @jmssaws @Definitive Dave

Also, nice oil pump mod. A lot of people here would be interested if you did a thread on that.

 

[BuckthornBonnie]

The damage to that cylinder doesn't look to have been caused by that piston, at least to me.

I'd replace it. Those look like deep scratches, not just transfer. They don't line up with the piston damage. Looks like it was reconditioned before it hit your buddy's saw.

064 cylinders aren't all that hard to come by. @jmssaws @Definitive Dave

Also, nice oil pump mod. A lot of people here would be interested if you did a thread on that.

I thought that initially as well.


Does your buddy know the story to this saw? I have seen marks on pistons with no corresponding marks on cylinders. But not usually the other way around (but I suppose it could happen).

 

[jmssaws]

Looks like it was trying to seize from a shot of gas that needed a little more oil or the can shaken up.

Clean the piston and cylinder up and run it.

 

[mdavlee]

I'd run it with a new piston

 

[421SD]

Thanks for the replies. My friend is not nice to equipment! It most likely happened while he had it. Not sure of cause. It ran fine for me the only issue I had was it didn't like to idle nose down or on its side. The idle would slow way down to almost stall. Couldn't get adjusted to stop that prob. That's why I started the investigation for the cause. It ran good other than that. Pulled 28" bar burried in a huge elm no problem. That's how I tested my frankin oiler out to make sure it would work.

 

[421SD]

I did a little scuffing with 600 grit. on the cylinder to see if the scratches were deep most of them came out with little effort but there are a few that are fairy deep. I put a new caber ring in to check the gap nice and tight, the rings that were in it had a lot of gap. The bottom ring was worse than the top. So big scratches on piston and cylinder and whipped rings and it still had 150+ comp. They are tougher than you think!

 

[blsnelling]

I'd be doing a vac test on that saw. That damage didn't come from a dirty air filter. It tried to lean seize, and now you mention tuning issues. Better safe than sorry.

 

[JonCraig]

Yes! Idle changing as you hold it different ways sounds like crank seals. I'd be replacing them as cheap insurance! (And pressure/vac testing before and after.)

Important to do both tests both before AND after replacing. Tons of info on this site in how to do it, and the tools aren't too pricey. Most frustrating part (for me) is making blocks to hold a piece of rubber to block off the intake & exhausts.